slobber
To let spit drip messily from your mouth.
Slobber means to let saliva (spit) drip messily from your mouth. Babies slobber when they're teething because they haven't learned to control their mouths yet. Dogs slobber when they're excited about food or when they see their favorite person coming home, leaving wet spots on your clothes or the floor.
The word captures that uncontrolled, drippy quality: saliva spilling out in a sloppy way. A mastiff watching someone eat a sandwich might slobber all over the kitchen floor. Some dog breeds, like Saint Bernards and bloodhounds, are famous slobberers because of how their jowls are shaped.
People sometimes use slobber figuratively to describe excessive enthusiasm that seems embarrassing or undignified. If someone is slobbering over a celebrity, they're showing so much admiration that it seems over the top and slightly ridiculous, like they've lost control of themselves the way a dog loses control around food.
The noun form is also slobber: you might wipe the slobber off a puppy's chin or find slobber on your shoe after your dog greeted you enthusiastically.